He has now come clean about it - contrary to what he had originally claimed, he didn't have any visa at all, and had been coming and going for some time on a tourist "visa" (actually visa waiver) while he was applying for a new work visa as a freelance - he was keen to emphasise that he had previously held a work visa, but that is hardly relevant since he had let it lapse without attempting a renewal. You won't be surprised to learn that tourists aren't really supposed to work while in Japan. In fact there is a certain amount of quasi-official blind-eye-turning to this, especially while someone with a genuine application is waiting for another visa to come through (as it happens I know of someone in this situation right now, not at my workplace though) but some people seem to survive more-or-less indefinitely with this status. The tourist visa is only valid for 90 days, so you have to leave the country for a few days every quarter, which in practice typically means a weekend in South Korea before returning for a new 90 day tour of duty. After a few trips, though, it must start to look suspicious, and there are many cautionary tales around the internet of people whose luck has run out.

I'm guessing immigration was particularly suspicious this time round because his last trip actually was a quick jaunt to South Korea - even though I have no reason not to believe that in his case it was actually a genuine work-related trip. He still had no visa and no fundamental right to come and work in Japan.

Of course one could legitimately question why Japan makes it so hard for a freelancer to get a visa. The bureaucracy has somewhat arbitrary rules - including typically the need for a single employer who promises an adequate salary - and someone who picks up bits and pieces from a number of sources might find it hard to satisfy this requirement. But the bottom line is, he had no visa, and no right to come and work here just because he had done so at some time in the past. As a claimed long-term resident fluent in the local language and culture, he should have realised the importance of keeping his paperwork up to date. And those of us who do make sure to keep our papers up to date certainly don't need to start worrying that some random functionary is suddenly going to stop us at the border and tell us we can't come home.

Lots of people are speculating that his dishonesty will harm his career prospects: my view of the press is sufficiently jaundiced that I suspect that the attention he has garnered will outweigh that. (More links via JP)